Molecular multiplicity of nuclease TT1 from Thermus thermophilus HB8

Purified nuclease TT1 from Thermus thermophilus HB8 has multimolecular weight forms, each of which is composed of three different subunits, alpha (10.8 x 10(4)), beta (7.8 x 10(4)), and gamma (4.1 x 10(4)). The molecular weights of this enzyme were estimated by gel filtration, polyacrylamide gel electrophoresis and equilibrium sedimentation. It was found that most of the enzyme has a molecular weight of about 22 x 10(4) being a monomer having the subunit composition of alpha beta gamma. The remaining part of the enzyme has larger molecular weights and is considered to be size-isomers of alpha beta gamma. The alpha-helical content, 5.5--6.5%, and the beta-structure, about 28%, were estimated from the CD spectrum at 4 degrees C.